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PARAMETRIC EQUATIONS DIFFERENTIATION. WJEC PAST PAPER PROBLEM (OLD P3) JUNE 2003. PAST PAPER P3 JUNE 2003. A curve has parametric equations. Show that the tangent to the curve at the point P, whose parameter is p, has equation:.
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PARAMETRIC EQUATIONS DIFFERENTIATION WJEC PAST PAPER PROBLEM (OLD P3) JUNE 2003
PAST PAPER P3 JUNE 2003 A curve has parametric equations Show that the tangent to the curve at the point P, whose parameter is p, has equation:
First find the gradient of the tangent at the point where the parameter is p
where the parameter is p we simply replace t with p This is the gradient of the TANGENT at the required point with parameter p
The equation of the tangent is found using the standard equation of a straight line: Where t=p The equation of the tangent is
THE QUESTION CONTINUES TO SAY: The tangent meets the x axis at A. Find the least value of the length OA, where O is the origin. When a line crosses the x axis we have the y coordinate as zero. USE y=0 in the equation of the tangent that we have just found.
When y=0 Of course the x coordinate IS the distance OA This will be a least value when cos p=1(the most that cos p can be) Because the most denominator gives the least fraction.
CONCLUDE BY SAYING: The least value of the distance OA is 2